Yanmar 1GM exhaust water flow - F25

Engines, Drive trains, Propellers, Steering, Ground Tackle and other mechanical system
Post Reply
User avatar
mscardwell
Posts: 6
Joined: Thu Jun 14, 2012 3:43 pm
Location: Memphis, Tennessee

Yanmar 1GM exhaust water flow - F25

Post by mscardwell »

Hi:

I have a suspicion that I have inadequate water flow through the engine - the amount of water exiting the exhaust at the transome looks miniscule and not what I think a good water flow should be. Last week I had the engine quit on me (it was very hot out, 101 degrees, and I had been running the engine for about 30 minutes at probably 75% rpm as I had to move her to a different marina and there was NO wind to assist), and after a half-hour of cool down, it fired up fine, but then started cutting out and dying again after 10 minutes. None of the guages/warning lights on the engine panel are operative (#116 on the to-do list on this little project boat), and so I am assuming it overheated given the context. It runs fine at idle ever since, but I still have little or no water flow.

My question is, what is a good troubleshooting scheme to try to isolate the problem? Before I break down (no pun intended!) and disassemble the water pump to check the impeller, are there any other steps I should take to find a problem elsewhere first? Also, is there any method out there to "blowback" through the line to clear any blockage that may be present below the waterline at the intake? This is the first inboard diesel I've dealt with, so I am operating with a steep learning curve (for now!).

Any thoughts or advice would be much appreciated!

Thanks,
Shawn
1982 Freedom 25 Winged Mast.

User avatar
GeoffSchultz
Posts: 1135
Joined: Thu Dec 04, 2008 8:39 am
Location: BlueJacket: Guatemala
Contact:

Re: Yanmar 1GM exhaust water flow - F25

Post by GeoffSchultz »

The steps that I'd take are:

1) Check the strainer.
2) Check the through-hull to make sure that it's not clogged by opening the strainer to check the flow through it.
3) Replace the impeller. Note that if the impeller has shredded, make sure that you find all of the parts that made it up, otherwise they may be between the raw water pump and the heat exchanger and are blocking the water flow.
4) Disassemble and rod out the heat exchanger.
5) Mixing elbow - but this is a last resort as steps 1-3 most likely will resolve it.

-- Geoff
BlueJacket
1997 Freedom 40/40
http://www.GeoffSchultz.org

User avatar
mscardwell
Posts: 6
Joined: Thu Jun 14, 2012 3:43 pm
Location: Memphis, Tennessee

Re: Yanmar 1GM exhaust water flow - F25

Post by mscardwell »

Thanks Geoff!

I will follow your steps this weekend and see what I can find. Very helpful advice, thanks.

Shawn
1982 Freedom 25 Winged Mast.

jbgiven
Posts: 2
Joined: Mon Nov 28, 2011 8:43 pm

Re: Yanmar 1GM exhaust water flow - F25

Post by jbgiven »

Shawn -
I had a similar over heating on my F25 but the overtemp alarm did sound.
Turns out the water intake was fowled and needed to be rodded out.
I am considering measuring water outflow peer your suggestion now that the problem has been corrected to establish a good base line water circulation.
By now I hope you problem is resolved.

Cheers,
Jim

Post Reply